The Na+/H+ exchange and H+ diffusion properties of human postmortem mucus: a comparison of gastric antral, gastric body, jejunal and ileal mucus.

The stomach and small intestine are areas of major electrolyte and solute transport. Mechanisms of transport in these areas have been widely studied and basic understanding is available. However, the mucus that lines the stomach and intestine is an important layer whose properties and functions in electrolyte and solute transport are not well understood. In this study we examined the Na+/H+ exchange of mucus from the stomach body and antrum, the jejunum, and the ileum. Mucus from the stomach body and antrum is a cation exchanger, a property that aids the net unidirectional flux of H+ ions from parietal cells to lumen. In the jejunum and ileum, mucus is an anion exchanger, which may be important in solute transport and absorption in the small bowel. In both the stomach and small bowel, proton movement is slow, which helps maintain the uphill pH gradient across gastric mucus and the downhill pH gradient across small intestinal mucus.